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Abstract:

Disclosed is a photovoltaic module with a bar-like external shape. The
photovoltaic module includes a main body section giving the bar-like
external shape, a photovoltaic element provided inside the main body
section, and output terminals formed at respective ends of the main body
section for output of electric power generated by the photovoltaic
element. The main body section is covered with a transparent synthetic
resin film.

Claims:

1. A photovoltaic module with a bar-like external shape, comprising: a
main body section forming the external shape; a photovoltaic element
provided inside the main body section; and output terminals provided on
respective ends of the main body section for output of electric power
generated by the photovoltaic element, wherein the main body section is
covered with a transparent synthetic resin film.

2. A photovoltaic system, comprising: a first group of photovoltaic
modules prepared by two-dimensionally arranging the photovoltaic modules
as set forth in claim 1 with intervals therebetween; and first holders
for holding the first group of photovoltaic modules.

3. A light admitting apparatus, comprising: a photovoltaic system as set
forth in claim 2; and a support section for supporting the photovoltaic
system.

Description:

TECHNICAL FIELD

[0001] The present invention relates to a photovoltaic module with a
bar-like external shape, a photovoltaic system including a plurality of
photovoltaic modules, and a light admitting apparatus including a
photovoltaic system.

BACKGROUND ART

[0002] Solar cells (photovoltaic systems) of various shapes have been
proposed for improved power generation efficiency to respond to
increasing interest in clean energy. The most popularly used ones are
those with a planar light receiving face for sunlight. Solar cells with
light receiving faces arranged in a cylindrical (columnar) form (as
opposed to planar light receiving faces) have also been proposed for
improved power generation cost (see, for example, Patent Documents 1 and
2).

[0003] An exemplary conventional photovoltaic system will be described in
reference to FIGS. 10A and 10B.

[0004] FIG. 10A is an oblique view of an arrangement of solar cell modules
in a conventional photovoltaic system.

[0005] FIG. 10B is a side view of the photovoltaic system shown in FIG.
10A as viewed from the lengthwise direction (arrangement direction) of
the solar cell modules.

[0006] The photovoltaic system 101 includes a plurality of cylindrical
solar cell modules 112 each extending in arrangement direction Df
(lengthwise direction) in a plane. The solar cell modules 112 are
supported by holders 115 at both ends. Sunlight, identified as
illumination light LS, changes its direction with time. However, since
sunlight moves along the cylinder's circumference, and the light
receiving condition of the solar cell modules 112 remains substantially
unchanged, relatively stable solar electric generation is possible. The
solar cell modules 112 are separated from each other by suitable
intervals so that they can receive sunlight equally even when the sun is
not shining directly from above.

[0007] The solar cell modules 112 are elevated to a height above an
installation surface RF by an installation member 140 so as to receive
sunlight. A reflection member RB is provided on the installation surface
RF to produce reflection (scattered light) which hits the
non-illumination light side (backside) of the solar cell modules 112. The
reflection member RB is formed of, for example, white paint.

[0008] The solar cell module (photovoltaic module) 112 is typically made
of a glass tube, and if installed outdoors, can be damaged due to a
mechanical impact from the surroundings and may produce scattered glass
fragments. There is also a demand to modify the photovoltaic system 101
including the solar cell modules 112 so that it is more broadly
applicable.

[0011] As mentioned above, the photovoltaic system 101 requires the
provision of the reflection member RB to produce reflection which hits
the non-illumination light side of the solar cell modules 112. In
addition, no power generation occurs in the intervals between the solar
cell modules 112, which is a cause of limitation in improvement of power
generation capability per unit area. A further issue is the need to
ensure safety when the solar cell module 112 is damaged.

[0012] The present invention, conceived in view of these problems, has an
object to provide a photovoltaic module capable of ensuring safety when
damaged, by providing a transparent synthetic resin film around a
bar-like photovoltaic module.

[0013] The present invention has another object to provide a photovoltaic
system capable of improving the power generation capability per unit area
of groups of two-dimensionally arranged bar-like photovoltaic modules
disposed where illumination light is shone, by overlapping the groups of
photovoltaic modules parallel to each other.

[0014] The present invention has a further object to provide a light
admitting apparatus capable of admitting light by applying the
photovoltaic modules in accordance with the present invention.

Solution to Problem

[0015] A photovoltaic module in accordance with the present invention is a
photovoltaic module with a bar-like external shape, the module including:
a main body section forming the external shape; a photovoltaic element
provided inside the main body section; and output terminals provided on
respective ends of the main body section for output of electric power
generated by the photovoltaic element, wherein the main body section is
covered with a transparent synthetic resin film.

[0016] According to the configuration, the photovoltaic module in
accordance with the present invention has a main body section with a
bar-like external shape covered with a transparent synthetic resin film.
Therefore, the transparent synthetic resin film covering the glass tube
restrains glass fragments from scattering and ensures safety if, for
example, the main body section is made of a member which can break like a
glass tube and damaged by any chance.

[0017] A photovoltaic system in accordance with the present invention is a
photovoltaic system, including: a first group of photovoltaic modules
prepared by two-dimensionally arranging the photovoltaic modules in
accordance with the present invention with intervals therebetween; and
first holders for holding the first group of photovoltaic modules.

[0018] According to the configuration, the photovoltaic system in
accordance with the present invention includes: a first group of
photovoltaic modules prepared by two-dimensionally arranging the
photovoltaic modules in accordance with the present invention with
intervals therebetween; and first holders for holding the first group of
photovoltaic modules. Therefore, solar electric generation is realized
which is very safe and efficient.

[0019] A light admitting apparatus in accordance with the present
invention is a light admitting apparatus including: a photovoltaic system
in accordance with the present invention including a plurality of
photovoltaic modules with a bar-like external shape; and a support
section for supporting the photovoltaic system.

[0020] According to the configuration, the light admitting apparatus in
accordance with the present invention both generates electricity from
solar energy and admits light, which adds to the usage of the
photovoltaic modules.

Advantageous Effects of the Invention

[0021] According to the photovoltaic module in accordance with the present
invention, the transparent synthetic resin film covering the glass tube
restrains glass fragments from scattering and ensures safety if, for
example, the main body section is made of a member which can break like a
glass tube and damaged by any chance.

[0022] According to the photovoltaic system in accordance with the present
invention, solar electricity generation is realized which is very safe
and efficient.

[0023] The light admitting apparatus in accordance with the present
invention both generates electricity from solar energy and admits light,
which adds to the usage of the photovoltaic modules.

BRIEF DESCRIPTION OF DRAWINGS

[0024] FIG. 1A is a schematic cross-sectional view of an internal
structure of a photovoltaic module in accordance with embodiment 1 of the
present invention.

[0025] FIG. 1B is a cross-sectional view of a variation of the
photovoltaic module shown in FIG. 1A where the extent of coverage
provided by a transparent synthetic resin film is modified.

[0026] FIG. 2A is an exploded perspective view of a first group of
photovoltaic modules and a second group of photovoltaic modules which
together constitute a photovoltaic system in accordance with embodiment 2
of the present invention, with the first and second groups being shown
detached from each other.

[0027] FIG. 2B is a side view of the photovoltaic system shown in FIG. 2A
as viewed from the lengthwise direction (arrangement direction) of the
first group of photovoltaic modules.

[0028] FIG. 2C is a plan view of the photovoltaic system shown in FIG. 2B
as viewed from an illumination light side.

[0029] FIG. 3A is an exploded perspective view of a first group of
photovoltaic modules and a second group of photovoltaic modules which
together constitute a photovoltaic system in accordance with embodiment 3
of the present invention, with the first and second groups being shown
detached from each other.

[0030] FIG. 3B is a side view of the photovoltaic system shown in FIG. 3A
as viewed from the lengthwise direction (arrangement direction) of the
first group of photovoltaic modules.

[0031] FIG. 3C is a plan view of the photovoltaic system shown in FIG. 3B
as viewed from an illumination light side.

[0032] FIG. 4 is a side view of a photovoltaic system in accordance with
embodiment 4 of the present invention, showing a gap between a first
group of photovoltaic modules and a second group of photovoltaic modules
which together constitute the photovoltaic system.

[0033] FIG. 5 is a side view of a photovoltaic system in accordance with
embodiment 5 of the present invention, showing relative positions of a
first group of photovoltaic modules, a second group of photovoltaic
modules, and a third group of photovoltaic modules which together
constitute the photovoltaic system.

[0034] FIG. 6 is a schematic cross-sectional partial view of first holders
connecting photovoltaic modules in accordance with embodiment 6 of the
present invention.

[0035] FIG. 7 is a schematic cross-sectional view of an internal structure
of the photovoltaic modules shown in FIG. 6.

[0036]FIG. 8A is a schematic and conceptual oblique view of a light
admitting apparatus (example 1) in accordance with embodiment 7 of the
present invention.

[0037] FIG. 8B is a schematic and conceptual oblique view of a light
admitting apparatus (example 2) in accordance with embodiment 7 of the
present invention.

[0038] FIG. 8C is a schematic and conceptual oblique view of a light
admitting apparatus (example 3) in accordance with embodiment 7 of the
present invention.

[0039] FIG. 8D is a schematic and conceptual oblique view of a light
admitting apparatus (example 4) in accordance with embodiment 7 of the
present invention.

[0040] FIG. 9A is a graph representing how light admittance changes in
relation to the path of the sun (altitude and direction) and the
arrangement of photovoltaic modules ((module diameter):(module
interval)=1:1).

[0041] FIG. 9B is a graph representing how a light admittance changes in
relation to the path of the sun (altitude and direction) and the
arrangement of photovoltaic modules ((module diameter):(module
interval)=1:1.6).

[0042] FIG. 10A is an oblique view of an arrangement of solar cell modules
in a conventional photovoltaic system.

[0043] FIG. 10B is a side view of the photovoltaic system shown in FIG.
10A as viewed from the lengthwise direction (arrangement direction) of
the solar cell modules.

DESCRIPTION OF EMBODIMENTS

[0044] The following will describe embodiments of the present invention in
reference to drawings.

Embodiment 1

[0045] FIG. 1A is a schematic cross-sectional view of an internal
structure of a photovoltaic module 12 in accordance with embodiment 1 of
the present invention.

[0046] FIG. 1B is a cross-sectional view of a variation of the
photovoltaic module 12 shown in FIG. 1A where the extent of coverage
provided by a transparent synthetic resin film 13p is modified.

[0047] The photovoltaic module 12 (main body section 13) in accordance
with the present embodiment has a bar-like external shape and includes a
photovoltaic element (e.g., solar cell element) provided inside the
bar-shaped exterior. Specifically, the photovoltaic module 12 includes
the main body section 13 and output terminals 14 provided on the ends of
the main body section 13. The output terminals 14 consists of an output
terminal 14f corresponding to an outer electrode 13f and an output
terminal 14s corresponding to an inner electrode 13s.

[0048] The main body section 13 is transparent so that it can admit
external illumination light LS (see FIGS. 2B and 3B) and made of, for
example, a cylindrical glass tube. The main body section 13 is preferably
cylindrical in order to ensure strength and also to allow sufficient
illumination light to uniformly illuminate the bar-like interior, in no
matter which direction the illumination light LS is traveling. The
cylinder has a diameter (outer circumference) of, for example,
approximately 20 mm to 40 mm and a length of, for example, approximately
1,000 mm. The cylinder has a sufficient thickness to ensure strength, for
example, approximately 1 mm.

[0050] The main body section 13 is covered with the transparent synthetic
resin film 13p. The provision of the transparent synthetic resin film 13p
reinforces the strength of the main body section 13 (glass tube 13g) and
restrains the glass tube 13g from breaking into fragments and scattering.
The transparent synthetic resin film 13p preferably covers all around the
glass tube 13g. The transparent synthetic resin film 13p, formed all
around the glass tube 13g, unfailingly protects the glass tube 13g. The
transparent synthetic resin film 13p preferably covers at least a half of
the glass tube 13g which faces the ground as shown in FIG. 1B. The
transparent synthetic resin film 13p, formed to cover a half of the glass
tube 13g which faces the ground, can be a precaution against falling and
other undesirable events.

[0051] The main body section 13 is by no means limited to a glass tube and
may be made of another transparent raw material, for example, an acrylic
resin or other plastic, a ceramic, or a like material. If the main body
section 13 is a glass tube 13g, the main body section 13 is preferably
covered with a transparent synthetic resin film 13p.

[0052] As mentioned above, the photovoltaic module 12 in accordance with
the present embodiment has a bar-like external shape and includes the
main body section 13 (e.g., glass tube 13g) forming the external shape,
the photovoltaic element (the outer electrode 13f, the photoelectric
conversion layer 13c, and the inner electrode 13s) provided inside the
main body section 13, and the output terminals 14 formed on the
respective ends of the main body section 13 for output of electric power
generated by the photovoltaic element. The main body section 13 is
covered with the transparent synthetic resin film 13p.

[0053] According to the photovoltaic module 12 in accordance with the
present embodiment, the main body section 13 with a bar-like external
shape is covered with the transparent synthetic resin film 13p.
Therefore, the transparent synthetic resin film 13p covering the glass
tube 13g restrains glass fragments from scattering and ensures safety if
for example, the main body section 13 is made of a member which can break
like a glass tube 13g and damaged by any chance.

[0054] Specifically, the transparent synthetic resin film 13p is
preferably a fluorine-based resin film. An alternative may be an ionomer
film (IO film), a polyethylene film (PE film), a polyvinyl chloride film
(PVC film), a polyvinylidene chloride film (PVDC film), a polyvinyl
alcohol film (PVA film), a polypropylene film (PP film), a polyester
film, a polycarbonate film (PC film), a polyacrylonitrile film (PAN
film), an ethylene-vinyl alcohol copolymer film (EVOH film), an
ethylene-methacrylic acid copolymer film (EMAA film), a nylon film (NY
film, polyamide (PA) film), or cellophane.

[0055] As a further alternative, the transparent synthetic resin film 13p
may be made of a photocatalytic coating material (titanium oxide
photocatalytic layer). The transparent synthetic resin film 13p, made of
a photocatalytic coating material, will likely keep itself free of dirt
which would otherwise degrade the properties of the transparent synthetic
resin film 13p.

[0056] An adhesive for use in applying the transparent synthetic resin
film 13p to the main body section 13 (glass tube 13g) may be, for
example, of a pressure sensitive, transparent type. The pressure
sensitive adhesive preferably contains a UV light absorbent. The use of a
UV light absorbent prevents film degradation.

[0057] The transparent synthetic resin film 13p is preferably formed to
meet the JIS standard for adhesive films for glazings (A5759).

[0058] The photovoltaic module 12 will be further described in embodiment
6.

Embodiment 2

[0059] Referring to FIGS. 2A to 2C, a photovoltaic system in accordance
with the present embodiment will be described. The present embodiment
will not depict any specific structure of the photovoltaic module 12 (the
photovoltaic module 22), and its details will be given later in relation
to FIGS. 6 and 7. However, since the photovoltaic module 12 in accordance
with embodiment 1 is applicable as is, the same reference signs and
numerals will be used.

[0060] FIG. 2A is an exploded perspective view of a first group 11 of
photovoltaic modules and a second group 21 of photovoltaic modules which
together constitute a photovoltaic system 1 in accordance with embodiment
2 of the present invention, with the first and second groups being shown
detached from each other.

[0061] FIG. 2B is a side view of the photovoltaic system 1 shown in FIG.
2A as viewed from the lengthwise direction (arrangement direction Df) of
the first group 11 of photovoltaic modules (photovoltaic modules 12).

[0062] FIG. 2C is a plan view of the photovoltaic system 1 shown in FIG.
2B as viewed from an illumination light LS side.

[0063] The photovoltaic system 1 in accordance with the present embodiment
includes a plurality of photovoltaic modules 12 with a bar-like external
shape (a plurality of photovoltaic modules 22 with a bar-like external
shape). The photovoltaic system 1 includes the first group 11 of
photovoltaic modules 12 which are arranged two-dimensionally with
intervals therebetween, the second group 21 of photovoltaic modules 22
which are arranged two-dimensionally with intervals therebetween, first
holders 15 for holding the first group 11 of photovoltaic modules, and
second holders 25 for holding the second group 21 of photovoltaic
modules. The first group 11 of photovoltaic modules is disposed on top
of, and parallel to, the second group 21 of photovoltaic modules.

[0064] According to the photovoltaic system 1 in accordance with the
present embodiment, a plurality of groups of two-dimensionally arranged
photovoltaic modules (e.g., the first group 11 of photovoltaic modules
and the second group 21 of photovoltaic modules) are disposed parallel to
each other with one on top of the other. If the first group 11 of
photovoltaic modules is disposed on a side illuminated by the
illumination light LS, since the second group 21 of photovoltaic modules
disposed on a non-illumination light side of the first group 11 of
photovoltaic modules acts as a reflection member which reflects light
toward the first group 11 of photovoltaic modules and produces reflection
(scattered light) toward the non-illumination light side of the first
group 11 of photovoltaic modules, the power generation capability per
unit area of the first group 11 of photovoltaic modules is improved.

[0065] Although the photovoltaic modules 12 and the photovoltaic modules
22 are given different reference numerals for convenience of description,
they are identical elements (photovoltaic modules) of the photovoltaic
system 1 (the first group 11 of photovoltaic modules and the second group
21 of photovoltaic modules). The "photovoltaic modules" in the
photovoltaic system 1 refers to both the photovoltaic modules 12 and the
photovoltaic modules 22.

[0066] In the first group 11 of photovoltaic modules, the photovoltaic
modules 12 are arranged two-dimensionally and preferably in a plane.
However, the arrangement is by no means limited to this. Alternatively,
the photovoltaic modules 12 may be arranged in a curved surface.
Likewise, in the second group 21 of photovoltaic modules, the
photovoltaic modules 22 are arranged two-dimensionally and preferably in
a plane. However, the arrangement is by no means limited to this.
Alternatively, the photovoltaic modules 22 may be arranged in a curved
surface.

[0067] Both the photovoltaic modules 12 and the photovoltaic modules 22
have a bar-like external shape so that they can receive a photovoltaic
output at their ends. The photovoltaic modules 12 (photovoltaic modules
22) will be further detailed in embodiment 6 (FIGS. 6 and 7).

[0068] The photovoltaic system 1 (the first group 11 of photovoltaic
modules and the second group 21 of photovoltaic modules) is elevated
vertically to a height above an installation surface RF by an
installation member 40. If the installation surface RF is a deck roof,
and the photovoltaic system 1 is installed outdoors, the illumination
light LS is sunlight and solar electric generation is possible.

[0069] Since the photovoltaic modules 12 and the photovoltaic modules 22
are shaped like a bar, even if the illumination light LS is sunlight and
moves (changes its direction) with time along the outer circumference of
the bar, the light receiving condition remains almost unchanged. That
stable light receiving condition enables stable solar electric
generation.

[0070] In the photovoltaic system 1 in accordance with the present
embodiment, the photovoltaic modules 12 in the first group 11 of
photovoltaic modules extend in arrangement direction Df (the lengthwise
direction of the bar-like external shape), and the photovoltaic modules
22 in the second group 21 of photovoltaic modules extend in arrangement
direction Ds (the lengthwise direction of the bar-like external shape).
Arrangement direction Df is parallel to arrangement direction Ds (see
FIG. 2C).

[0071] Therefore, according to the photovoltaic system 1 in accordance
with the present embodiment, the photovoltaic modules 22 which constitute
the second group 21 of photovoltaic modules are located in the intervals
of the photovoltaic modules 12 which constitute the first group 11 of
photovoltaic modules if projected onto a plane (e.g., when viewed from
the illumination light LS side). The intervals of the photovoltaic
modules (those of the photovoltaic modules 12 and those of the
photovoltaic modules 22) are efficiently utilized. That allows for
installation of more photovoltaic modules per unit area, and hence
improves the power generation capability per unit area of the whole set
of photovoltaic modules (the photovoltaic modules 12 and the photovoltaic
modules 22). In other words, the efficient use of the intervals of the
photovoltaic modules 12 and those of the photovoltaic modules 22 improves
the power generation efficiency per unit area of the photovoltaic system
1.

[0072] Conventional technology requires the provision of a reflection
member RB on the installation surface RF (see FIG. 10B). In contrast, the
photovoltaic system 1 in accordance with the present embodiment requires
no reflection member RB that is conventionally essential (see FIG. 10B)
because the second group 21 of photovoltaic modules forms a reflection
surface for the first group 11 of photovoltaic modules. A reflection
member (not shown) for the second group 21 of photovoltaic modules may be
provided.

[0073] The intervals of the two-dimensionally arranged photovoltaic
modules 12 and those of the two-dimensionally arranged photovoltaic
modules 22 are preferably not so narrow that the photovoltaic modules 12
and the photovoltaic modules 22 can overlap when the first group 11 of
photovoltaic modules is disposed on top of the second group 21 of
photovoltaic modules (see FIG. 2C).

[0074] The intervals of the photovoltaic modules 12 and those of the
photovoltaic modules 22 are preferably all equal. The same interval is
preferably repeated for all the photovoltaic modules 12 and the
photovoltaic modules 22.

[0075] The non-overlapping disposition of the photovoltaic modules 12 and
the photovoltaic modules 22 maximizes illumination efficiency (area usage
efficiency) when the illumination light LS illuminates from the front
(perpendicularly to the top face (plane) of the photovoltaic system 1).
The provision of the intervals between the photovoltaic modules 12 in the
first group 11 of photovoltaic modules increases the illumination light
LS reaching the second group 21 of photovoltaic modules. That also
improves the power generation capability per unit area.

[0076] On the other hand, if the intervals of the photovoltaic modules 12
and the photovoltaic modules 22 are too wide, the first group 11 of
photovoltaic modules (the second group 21 of photovoltaic modules)
requires a greater footprint. Thus, the power generation capability per
unit area is reduced. For these reasons, it is preferable if the
intervals are specified properly according to the needs and conditions of
the place where the photovoltaic system 1 is installed.

[0077] In the photovoltaic system 1, the shape of the two-dimensional
arrangement (two-dimensional shape) of the photovoltaic modules 12 in the
first group 11 of photovoltaic modules and the shape of the
two-dimensional arrangement (two-dimensional shape) of the photovoltaic
modules 22 in the second group 21 of photovoltaic modules are preferably
identical.

[0078] In the photovoltaic system 1 in accordance with the present
embodiment, since the shape of the two-dimensional arrangement of the
photovoltaic modules 12 in the first group 11 of photovoltaic modules and
the shape of the two-dimensional arrangement of the photovoltaic modules
22 in the second group 21 of photovoltaic modules are identical, the
groups of photovoltaic modules (the first group 11 of photovoltaic
modules and the second group 21 of photovoltaic modules) wherein the
first group 11 of photovoltaic modules and the second group 21 of
photovoltaic modules have the same two-dimensional shape and overlap are
easy to assemble and easy to install.

[0079] The shape of the two-dimensional arrangement (two-dimensional
shape) of the photovoltaic modules 12 in the first group 11 of
photovoltaic modules and the shape of the two-dimensional arrangement
(two-dimensional shape) of the photovoltaic modules 22 in the second
group 21 of photovoltaic modules may be specified as a shape (peripheral
shape) so as to include the first holders 15 and the second holders 25.

[0080] If the first group 11 of photovoltaic modules (photovoltaic modules
12) and the second group 21 of photovoltaic modules (photovoltaic modules
22) contain the same number of photovoltaic modules (the same
two-dimensional arrangement and the same two-dimensional shape), the
photovoltaic modules 12 and the photovoltaic modules 22 are preferably
disposed so that they do no overlap when the first group 11 of
photovoltaic modules is disposed on top of the second group 21 of
photovoltaic modules.

[0081] If the first holders 15 holding the photovoltaic modules 12 (the
first group 11 of photovoltaic modules) have the same arrangement as the
second holders 25 holding the photovoltaic modules 22 (the second group
21 of photovoltaic modules), and the first holders 15 are disposed on top
of the second holders 25, the photovoltaic modules 12 are disposed as
such on top of the photovoltaic modules 22. Accordingly, either the first
group 11 or the second group 21 (e.g., the first group 11 of photovoltaic
modules) may be a mirror image of the other (the second group 21 of
photovoltaic modules) (see FIGS. 2B and 2C) so that the photovoltaic
modules 12 (the first group 11 of photovoltaic modules) and the
photovoltaic modules 22 (the second group 21 of photovoltaic modules) do
not overlap in the plan view when viewed from the illumination light LS
direction even if the photovoltaic modules 12 and 22 have the same
two-dimensional arrangement (the same two-dimensional shape).

[0082] The number of the photovoltaic modules 12 in the first group 11 of
photovoltaic modules may differ from the number of the photovoltaic
modules 22 in the second group 21 of photovoltaic modules.

[0083] As mentioned above, the photovoltaic system 1 in accordance with
the present embodiment includes at least two faces, one formed by the
first group 11 of photovoltaic modules 12 and the other by the second
group 21 of photovoltaic modules 22, the two faces being separated
vertically and mutually parallel.

[0084] Alternatively, if the photovoltaic modules 12 in accordance with
embodiment 1 are used, the photovoltaic system 1 in accordance with the
present embodiment may include a single face formed by the vertically
arranged, first group 11 of the photovoltaic modules 12.

[0085] The photovoltaic system 1 in accordance with the present embodiment
is preferably a photovoltaic system 1 including a plurality of
photovoltaic modules 12 with a bar-like external shape, the system
including: a first group 11 of photovoltaic modules (a group of
photovoltaic modules) in which the plurality of photovoltaic modules 12
are arranged two-dimensionally with intervals therebetween; and first
holders 15 (holders) for holding the first group 11 of photovoltaic
modules, wherein the photovoltaic modules 12 are those in accordance with
embodiment 1.

[0086] Hence, the photovoltaic system 1 in accordance with the present
embodiment includes: a first group 11 of photovoltaic modules (a group of
photovoltaic modules) in which the photovoltaic modules 12 in accordance
with embodiment 1 are arranged two-dimensionally with intervals
therebetween; and first holders 15 (holders) for holding the first group
11 of photovoltaic modules. The photovoltaic system 1 is therefore very
safe and efficient.

Embodiment 3

[0087] Referring to FIGS. 3A to 3C, a photovoltaic system in accordance
with the present embodiment will be described.

[0088] A photovoltaic system 1 in accordance with the present embodiment
has a similar basic configuration to that of the photovoltaic system 1 in
accordance with embodiment 2. Hence, the same reference numerals will be
used, and the description will focus on major differences. The
photovoltaic modules 12 in accordance with embodiment 1 are used as such
in the present embodiment as in embodiment 2.

[0089] FIG. 3A is an exploded perspective view of a first group 11 of
photovoltaic modules and a second group 21 of photovoltaic modules which
together constitute a photovoltaic system 1 in accordance with embodiment
3 of the present invention, with the first and second groups 11 and 21
being shown detached from each other.

[0090] FIG. 3B is a side view of the photovoltaic system 1 shown in FIG.
3A as viewed from the lengthwise direction (arrangement direction Df) of
the first group 11 of photovoltaic modules 12.

[0091] FIG. 3C is a plan view of the photovoltaic system 1 shown in FIG.
3B as viewed from an illumination light LS side.

[0092] The photovoltaic system 1 in accordance with the present embodiment
includes a plurality of photovoltaic modules 12 with a bar-like external
shape and a plurality of photovoltaic modules 22 with a bar-like external
shape. The photovoltaic system 1 includes the first group 11 of
photovoltaic modules 12 which are arranged two-dimensionally with
intervals therebetween, the second group 21 of photovoltaic modules 22
which are arranged two-dimensionally with intervals therebetween, first
holders 15 for holding the first group 11 of photovoltaic modules, and
second holders 25 for holding the second group 21 of photovoltaic
modules. The first group 11 of photovoltaic modules is disposed on top
of, and parallel to, the second group 21 of photovoltaic modules.

[0093] According to the photovoltaic system 1 in accordance with the
present embodiment, a plurality of groups of photovoltaic modules (e.g.,
the first group 11 of photovoltaic modules and the second group 21 of
photovoltaic modules) are disposed parallel to each other with one on top
of the other. If the first group 11 of photovoltaic modules is disposed
on a side illuminated by the illumination light LS, since the second
group 21 of photovoltaic modules disposed on a non-illumination light
side of the first group 11 of photovoltaic modules acts as a reflection
member which reflects light toward the first group 11 of photovoltaic
modules and produces reflection (scattered light) toward the
non-illumination light side of the first group 11 of photovoltaic
modules, the power generation capability per unit area of the first group
11 of photovoltaic modules is improved.

[0094] In the photovoltaic system 1 in accordance with the present
embodiment, the photovoltaic modules 12 in the first group 11 of
photovoltaic modules extend in arrangement direction Df (the lengthwise
direction of the bar-like external shape), and the photovoltaic modules
22 in the second group 21 of photovoltaic modules extend in arrangement
direction Ds (the lengthwise direction of the bar-like external shape).
Arrangement direction Df intersects arrangement direction Ds (see FIG.
3C).

[0095] Therefore, according to the photovoltaic system 1 in accordance
with the present embodiment, the photovoltaic modules 22 which constitute
the second group 21 of photovoltaic modules extend in arrangement
direction Ds which intersects arrangement direction Df in which the
photovoltaic modules 12 which constitute the first group 11 of
photovoltaic modules extend when projected onto a plane (e.g., when
viewed from the illumination light LS side). Therefore, the photovoltaic
system 1 further reduces adverse effect of the ever-changing illumination
light LS (such as, sunlight) to improve power generation efficiency.

[0096] In the photovoltaic system 1, the shape of the two-dimensional
arrangement (two-dimensional shape) of the photovoltaic modules 12 in the
first group 11 of photovoltaic modules and the shape of the
two-dimensional arrangement (two-dimensional shape) of the photovoltaic
modules 22 in the second group 21 of photovoltaic modules are preferably
identical.

[0097] In the photovoltaic system 1 in accordance with the present
embodiment, since the shape of the two-dimensional arrangement of the
photovoltaic modules 12 in the first group 11 of photovoltaic modules and
the shape of the two-dimensional arrangement of the photovoltaic modules
22 in the second group 21 of photovoltaic modules are identical, the
groups of photovoltaic modules (the first group 11 of photovoltaic
modules and the second group 21 of photovoltaic modules) wherein the
first group 11 of photovoltaic modules and the second group 21 of
photovoltaic modules have the same two-dimensional shape and overlap are
easy to assemble and easy to install.

[0098] The shape of the two-dimensional arrangement (two-dimensional
shape) of the photovoltaic modules 12 in the first group 11 of
photovoltaic modules and the shape of the two-dimensional arrangement
(two-dimensional shape) of the photovoltaic modules 22 in the second
group 21 of photovoltaic modules may be specified as a shape (peripheral
shape) so as to include the first holders 15 and the second holders 25.

[0099] Since the peripheral shapes which include the first holders 15 and
the second holders 25 are identical, the first group 11 including the
first holders 15 and the second group 21 including the second holders 25
can overlap by rotating the first group 11 of photovoltaic modules by
90° with respect to the second group 21 of photovoltaic modules or
conversely rotating the second group 21 of photovoltaic modules by
90° with respect to the first group 11 of photovoltaic modules.

[0100] Therefore, the first group 11 of photovoltaic modules with the
first holders 15 being attached thereto and the second group 21 of
photovoltaic modules with the second holders 25 being attached thereto
preferably have a square shape.

[0101] Unlike embodiment 2, arrangement direction Df in which the
photovoltaic modules 12 extend intersects arrangement direction Ds in
which the photovoltaic modules 22 extend in the present embodiment. When
the photovoltaic modules 12 and the photovoltaic modules 22 have the same
two-dimensional arrangement, the arrangement of the first holders 15 and
the arrangement of the second holders 25 have different shapes if the
two-dimensional shapes are rectangular, and the first group 11 of
photovoltaic modules with the first holders 15 being attached thereto is
disposed on top of the second group 21 of photovoltaic modules with the
second holders 25 being attached thereto. Therefore, the reflection from
the second group 21 of photovoltaic modules disposed below may not reach
the first group 11 of photovoltaic modules in sufficient quantity.

[0102] Therefore, the two-dimensional shape of the first group 11 of
photovoltaic modules and that of the second group 21 of photovoltaic
modules preferably match, so that the reflection from the second group 21
of photovoltaic modules disposed below can reach the first group 11 of
photovoltaic modules in sufficient quantity. Specifically, the
two-dimensional shape of the photovoltaic modules 12 together with the
first holders 15 supporting the photovoltaic modules 12 and the
two-dimensional shape of the photovoltaic modules 22 together with the
second holders 25 supporting the photovoltaic modules 22 preferably have
equal lengths and widths to form a square, so that a square (see FIG. 3C)
is formed when the photovoltaic modules 12 (the first group 11 of
photovoltaic modules) are disposed on top of, and so as to intersect, the
photovoltaic modules 22 (the second group 21 of photovoltaic modules).

[0103] If the first group 11 of photovoltaic modules and the second group
21 of photovoltaic modules are to form a square external shape state
(outer circumference state in the plan view) when the group 11 is
disposed on top of the group 21, the first group 11 of photovoltaic
modules and the second group 21 of photovoltaic modules should be
prepared so as to have substantially identical shapes (lengths and
widths) (squares of substantially identical size) in the plan view and
disposed with one on top of the other with 90° different
orientations. Hence, the photovoltaic system 1 improves productivity and
is easy to install.

[0104] The first group 11 of photovoltaic modules and the second group 21
of photovoltaic modules are by no means limited to square shapes and may
be rectangular.

Embodiment 4

[0105] Referring to FIG. 4, a photovoltaic system in accordance with the
present embodiment will be described.

[0106] A photovoltaic system 1 in accordance with the present embodiment
has a similar basic configuration to that of the photovoltaic system 1 in
accordance with embodiments 2 and 3. Hence, the same reference numerals
will be used, and the description will focus on major differences. The
photovoltaic system 1 in accordance with the present embodiment is
applicable to embodiments 2 and 3. In addition, the photovoltaic modules
12 in accordance with embodiment 1 are applicable to the present
embodiment as well as to embodiments 2 and 3.

[0107] FIG. 4 is a side view of the photovoltaic system 1 in accordance
with embodiment 4 of the present invention, showing a gap SP between a
first group 11 of photovoltaic modules and a second group 21 of
photovoltaic modules which together constitute the photovoltaic system 1.

[0108] In the photovoltaic system 1 in accordance with the present
embodiment, the gap SP between the first group 11 of photovoltaic modules
and the second group 21 of photovoltaic modules is preferably specified
to be greater than the size SC of an external shape in the direction in
which the first group 11 of photovoltaic modules is disposed on top of
the second group 21 of photovoltaic modules (the size of the external
shape in the direction which intersects the lengthwise direction of the
photovoltaic modules 12, the size of the external shape in the direction
which intersects the lengthwise direction of the photovoltaic modules
22).

[0109] The photovoltaic system 1 in accordance with the present embodiment
has a sufficient gap SP between the first group 11 of photovoltaic
modules and the second group 21 of photovoltaic modules. The structure
allows for an increased amount of light being uniformly reflected
(scattered) between the first group 11 of photovoltaic modules and the
second group 21 of photovoltaic modules. Hence, the power generation
capability per unit area of the first group 11 of photovoltaic modules
and the second group 21 of photovoltaic modules is surely improved.

[0110] The gap SP is provided by inserting proper spacers between first
holders 15 and second holders 25.

Embodiment 5

[0111] Referring to FIG. 5, a photovoltaic system in accordance with the
present embodiment will be described.

[0112] A photovoltaic system 1 in accordance with the present embodiment
has a similar basic configuration to that of the photovoltaic system 1 in
accordance with embodiments 2 to 4. Hence, the same reference numerals
will be used, and the description will focus on major differences. The
photovoltaic system 1 in accordance with the present embodiment is also
applicable to embodiments 2 to 4. In addition, the photovoltaic modules
12 in accordance with embodiment 1 are applicable to the present
embodiment as well as to embodiments 2 to 4.

[0113] FIG. 5 is a side view of the photovoltaic system 1 in accordance
with embodiment 5 of the present invention, showing relative positions of
a first group 11 of photovoltaic modules, a second group 21 of
photovoltaic modules, and a third group 31 of photovoltaic modules which
together constitute the photovoltaic system 1.

[0114] The photovoltaic system 1 in accordance with the present embodiment
is by no means limited to the two planes formed by the first group 11 of
photovoltaic modules and the second group 21 of photovoltaic modules (a
plane is formed by the photovoltaic modules 12, and another plane is
formed by the photovoltaic modules 22). The photovoltaic system 1 may
have a third layer.

[0115] Specifically, the photovoltaic system 1 in accordance with the
present embodiment includes the third group 31 of photovoltaic modules as
well as the first group 11 of photovoltaic modules and the second group
21 of photovoltaic modules. The third group 31 of photovoltaic modules
includes photovoltaic modules 32 which are arranged two-dimensionally
with intervals therebetween. The third group 31 of photovoltaic modules
is held by third holders 35.

[0116] In other words, the third group 31 of photovoltaic modules is
structured similarly to the first group 11 of photovoltaic modules and
the second group 21 of photovoltaic modules. The photovoltaic modules 32
are arranged similarly to the photovoltaic modules 12 and the
photovoltaic modules 22.

[0117] More layers may be provided by increasing the gaps between the
first group 11 of photovoltaic modules, the second group 21 of
photovoltaic modules, and the third group 31 of photovoltaic modules. In
addition, if the first group 11 of photovoltaic modules, the second group
21 of photovoltaic modules, and the third group 31 of photovoltaic
modules are to be configured to form respective curved surfaces, it is
more effective.

Embodiment 6

[0118] Referring to FIGS. 6 and 7, the following will describe, as
embodiment 6, first holders 15 which hold photovoltaic modules 12 with a
bar-like external shape (photovoltaic modules as elements for the
photovoltaic system 1) and photovoltaic modules 12 (a first group 11 of
photovoltaic modules). The photovoltaic modules 12 and the first holders
15 are applicable as such to the photovoltaic system 1 in accordance with
embodiments 2 to 5. Detailed description of the photovoltaic system 1 may
be omitted where appropriate.

[0119] Photovoltaic modules 22, second holders 25 holding the photovoltaic
modules 22 (embodiments 2 to 4), photovoltaic modules 32, and third
holders 35 holding and the photovoltaic modules 32 (embodiment 5) are
structured similarly to the photovoltaic modules 12 and the first holders
15. The description will therefore focus on the photovoltaic modules 12
and the first holders 15.

[0120] FIG. 6 is a schematic cross-sectional partial view of the first
holders 15 connecting the photovoltaic modules 12 in accordance with
embodiment 6 of the present invention.

[0121] FIG. 7 is a schematic cross-sectional view of an internal structure
of the photovoltaic modules 12 shown in FIG. 6.

[0122] The photovoltaic module 12 in accordance with the present
embodiment has a bar-like external shape and includes a photovoltaic
element (e.g., solar cell element) provided inside the bar-shaped
exterior. Specifically, the photovoltaic module 12 includes a main body
section 13 and output terminals 14 provided on the ends of the main body
section 13. The output terminals 14 consists of an output terminal 14f
corresponding to an outer electrode 13f (FIG. 7) and an output terminal
14s corresponding to an inner electrode 13s (FIG. 7).

[0123] The output terminal 14f (one of the output terminals 14) is
connected to a wire 16 formed on the first holder 15 holding one of the
ends of a photovoltaic module 12. The output terminal 14s (the other one
of the output terminals 14) is connected to a wire 16 formed on the first
holder 15 holding the other end of the photovoltaic module 12. In this
connection mode where the outer electrodes 13f are provided in one of the
first holders 15 and the inner electrodes 13s are provided in the other
one of the first holders 15, the photovoltaic modules 12 are preferably
connected in parallel in the first group 11 of photovoltaic modules.

[0124] The connection mode of the output terminals 14f and the output
terminals 14s is by no means limited to this connection mode.
Alternatively, when the output terminals 14f and the output terminals 14s
are in a connection mode where an alternate one of the output terminals
14f and 14s is positioned for output to one of the first holders 15
(wires 16), the photovoltaic modules 12 may be connected in series in the
first group 11 of photovoltaic modules.

[0125] The first holder 15 preferably has an open groove on a face thereof
where the photovoltaic modules 12 are positioned and inserted. With such
a groove, the first holder 15 is only open on its face facing the
photovoltaic modules 12, with the other faces being closed to the
outside. The structure allows for stable connection to the photovoltaic
modules 12 by eliminating external influence.

[0126] The provision of the wires 16 inside the first holder 15 enables
the first holder 15 to provide easy access to the solar electric power
output of the photovoltaic modules 12 (the first group 11 of photovoltaic
modules) as well as to hold the photovoltaic modules 12 (the first group
11 of photovoltaic modules). The provision also enables elimination of
external influence and safe output, thereby ensuring weatherability and
reliability of the photovoltaic system 1.

[0127] The main body section 13 is transparent so that it can admit
external illumination light LS (see FIGS. 2B and 3B) and made of, for
example, a cylindrical glass tube. The main body section 13 is preferably
cylindrical in order to ensure strength and also to allow sufficient
illumination light to uniformly illuminate the bar-like interior, in no
matter which direction the illumination light LS is traveling. The
cylinder has a diameter (outer circumference) of, for example,
approximately 20 mm to 40 mm and a length of, for example, approximately
1,000 mm. The cylinder has a sufficient thickness to ensure strength, for
example, approximately 1 mm.

[0129] The main body section 13 is by no means limited to a glass tube and
may be made of another transparent raw material, for example, an acrylic
resin or other plastic, a ceramic, or a like material.

[0130] The outer electrode 13f is composed of, for example, ITO (indium
tin oxide) or a like transparent material because it needs to allow
illumination light to be incident to the internally disposed
photoelectric conversion layer 13c. The photoelectric conversion layer
13c is, for example, a compound semiconductor layer and composed of
CuInGaSe. The inner electrode 13s is composed of, for example, Mo. This
particular structure is known as a CIGS solar cell.

[0131] The photovoltaic element in the photovoltaic module 12 is by no
means limited to a CIGS solar cell and may be of any type including
silicon and compound semiconductor solar cells.

[0132] As mentioned above, in the photovoltaic system 1, the photovoltaic
module 12 (the photovoltaic module 12 with a bar-like external shape)
preferably has a cylindrical external shape. This particular shape gives
necessary and sufficient mechanical strength and weatherability to the
photovoltaic system 1 in accordance with the present embodiment, thereby
enabling outdoor installation for solar electric generation.

[0133] So far in the present embodiment, the main body section 13 which
defines the external shape of the photovoltaic module 12 has been
described as being shaped like a bar and specifically like a (hollow)
cylinder (tube). Alternatively, the main body section 13 may be shaped
like an elliptic or polygonal cylinder (tube), or the like. In addition,
a cylinder (tube) in this context is not necessarily hollow and may be of
a solid circular, elliptic, or polygonal column which contains therein an
electrode and a photoelectric conversion section.

[0134] As mentioned above, the photovoltaic module 12 in accordance with
the present embodiment is applied as such to the photovoltaic system 1 in
accordance with embodiments 2 to 5 so as to act as a part of the
photovoltaic system 1.

[0135] Specifically, in the photovoltaic system 1, the first holders 15,
the second holders 25, and the third holders 35 include wires (e.g., the
wires 16 for the first holders 15) connected to output terminals (e.g.,
the output terminals 14 of the photovoltaic modules 12) of photovoltaic
modules (the photovoltaic modules 12, the photovoltaic modules 22, and
the photovoltaic modules 32). Therefore, the photovoltaic system 1 in
accordance with the present embodiment can surely collect generated
electric power with improved reliability.

[0136] Embodiments 2 to 6 in accordance with the present invention have
been detailed so far. The present invention is by no means limited to
those embodiments and variations, and encompasses in its scope design and
other modifications that do not depart from the spirit of the present
invention.

[0137] In relation to the photovoltaic module 12 in accordance with the
present embodiment, the description has not mentioned anything about the
transparent synthetic resin film 13p provided on the photovoltaic module
12 in accordance with embodiment 1. However, the transparent synthetic
resin film 13p is also applied as such in the present embodiment.

Embodiment 7

[0138] Referring to FIGS. 8A to 9B, a light admitting apparatus 50 in
accordance with the present embodiment will be described. The light
admitting apparatus 50 is a photovoltaic system 1 including a plurality
of photovoltaic modules 12 (see other embodiments) which is applied to an
artificial apparatus (a greenhouse WR in FIG. 8A, a top roof RFu disposed
on a top RF in FIG. 8B, a building-connecting roof RFb disposed between
buildings in FIG. 8C, a terrace roof TR disposed over a terrace in FIG.
8D) so as to reduce for example, sunlight reaching plants PL.

[0139]FIG. 8A is a schematic and conceptual oblique view of a light
admitting apparatus 50 (example 1) in accordance with embodiment 7 of the
present invention.

[0140] Plants PL are planted in the greenhouse WR. The greenhouse WR
includes a framework WR1 defining an external shape and sheltering
surfaces WR2 arranged on the framework WR1 to provide the internal space
of the greenhouse WR with shelter from external environment. The
sheltering surfaces WR2 are formed of, for example, a transparent film.

[0141] The light admitting apparatus 50 (photovoltaic system 1,
photovoltaic modules 12) in accordance with example 1 is disposed on the
top face of the greenhouse WR via a support section 51. Therefore,
external light (e.g., sunlight) is admitted to the space in the
greenhouse WR. Light admittance will be described in relation to FIGS. 9A
and 9B (and so it will for example 2 to example 4 below).

[0142] FIG. 8B is a schematic and conceptual oblique view of a light
admitting apparatus 50 (example 2) in accordance with embodiment 7 of the
present invention.

[0143] A plant PL, as an example, is disposed on a top RF of a building
BL. The light admitting apparatus 50 (the photovoltaic system 1, the
photovoltaic modules 12) is provided via the support section 51 to shield
the plant PL. The light admitting apparatus 50 forms the top roof RFu on
the top face of the support section 51. Therefore, the light admitting
apparatus 50 admits light for the plant PL and acts as a light admitting
apparatus.

[0144] FIG. 8C is a schematic and conceptual oblique view of a light
admitting apparatus 50 (example 3) in accordance with embodiment 7 of the
present invention.

[0145] A space is provided between a building 1 and a building 2, and a
building-connecting roof RFb is provided between a top RF of the building
1 and a top RF of the building 2. A plant PL, as an example, is planted
in the ground under the building-connecting roof RFb. The
building-connecting roof RFb is disposed over the plant PL and may
therefore shade the plant PL. The building-connecting roof RFb acting as
a support section 51, however, is provided with the light admitting
apparatus 50 (the photovoltaic system 1, the photovoltaic modules 12)
which acts as a light admitting apparatus for the plant PL.

[0146] FIG. 8D is a schematic and conceptual oblique view of a light
admitting apparatus 50 (example 4) in accordance with embodiment 7 of the
present invention.

[0147] A terrace roof TR is provided over a terrace TS of a house HS. A
plant PL, as an example, is planted in the terrace TS under the terrace
roof TR. The terrace roof TR acting as a support section 51 is provided
with the light admitting apparatus 50 (the photovoltaic system 1, the
photovoltaic modules 12) which acts as a light admitting apparatus for
the plant PL.

[0148] As illustrated in FIGS. 8A to 8D above, the light admitting
apparatus 50 in accordance with the present embodiment includes the
photovoltaic modules 12 with a bar-like external shape, the apparatus 50
including: the photovoltaic system 1 including a plurality of the
photovoltaic modules 12; and a support section 51 for supporting the
photovoltaic system 1, wherein the photovoltaic modules 12 are the
photovoltaic modules in accordance with embodiments 1 to 6, and the
photovoltaic system 1 is the photovoltaic system 1 in accordance with
embodiments 2 to 6.

[0149] Therefore, the light admitting apparatus 50 in accordance with the
present embodiment both generates electricity from solar energy and
admits light, which adds to the usage of the photovoltaic modules 12.
Next, in reference to FIGS. 9A and 9B, the following will describe light
admittance being controlled through the arrangement of the photovoltaic
modules 12.

[0150] FIG. 9A is a graph representing how light admittance changes in
relation to the path of the sun (altitude and direction) and the
arrangement of the photovoltaic modules 12 ((module diameter):(module
interval)=1:1).

[0151] The graph shows the sun's direction along its path (from
-120° to the east through 0° (culmination) to -120°
to the west) on the horizontal axis and the sun's altitude (from
0° to 90°) on the vertical axis. The curved line SC1
represents the path of the sun on the summer solstice. The curved line
SC2 represents the path of the sun on the winter solstice. The bar
parallel to the horizontal axis represents a relative ratio of admission
area and shield area. The graph represents data for Japan (Tokyo). Time
(6 h to 18 h) is plotted on the curved lines. The same explanation
applies to FIG. 9B.

[0152] FIG. 9A shows a relationship, for the sun's path, between the
shield area where sunlight is blocked and the admission area where
sunlight is admitted when the photovoltaic modules 12 are arranged so
that (module diameter):(module interval)=1:1.

[0153] On the summer solstice, the admission area is 40%, and the shield
area is 60% at noon (12 h); the admission area is 10%, and the shield
area is 90% at 9 h; and the admission area is 10%, and the shield area is
90% at 15 h. In other words, the light admittance is 40% at noon and 10%
at 9 h and 15 h.

[0154] FIG. 9B is a graph representing how light admittance changes in
relation to the path of the sun (altitude and direction) and the
arrangement of the photovoltaic modules 12 ((module diameter): (module
interval)=1:1.6).

[0155] FIG. 9B shows a relationship, for the sun's path, between the
shield area where sunlight is blocked and the admission area where
sunlight is admitted when the photovoltaic modules 12 is arranged so that
(module diameter):(module interval)=1:1.6.

[0156] On the summer solstice, the admission area is 60%, and the shield
area is 40% at noon (12 h); the admission area is 30%, and the shield
area is 70% at 9 h; and the admission area is 30%, and the shield area is
70% at 15 h. In other words, the light admittance is 60% at noon and 30%
at 9 h and 15 h.

[0157] Therefore, as shown in FIGS. 9A and 9B, the ratio of the admission
area and the shield area can be changed by modifying the arrangement of
the photovoltaic modules 12 (proportion of module interval to module
diameter). In other words, the light admittance (Admission
Area/(Admission Area+Shield Area)) can be changed.

[0158] A typical flat installation type of solar cell module cannot be
configured as a light admitting apparatus for some reasons including the
solar cells being fixed in a plane in the solar cell module and light
being blocked by the surface on which the solar cell modules are
disposed. In contrast, according to the photovoltaic modules 12 in
accordance with the present embodiment, the photovoltaic system 1 is
configured which has intervals between the photovoltaic modules 12, and
the intervals can be used to configure the light admitting apparatus 50.

[0159] The arrangement of the photovoltaic modules 12 may be modified as
needed by, for example, altering the intervals of the photovoltaic
modules 12 or altering the relative positions of the first holders 15
holding the photovoltaic modules 12, the second holders 25, and the third
holders 35.

[0160] The light admitting apparatus 50 is capable of efficiently
admitting sunlight for plants during the course of the day if the
intervals of the photovoltaic modules 12 are adjusted according to the
sun's path (direction).

[0161] In the spring and autumn when demand on the photovoltaic system 1
for power generation is relatively low, the intervals of the photovoltaic
modules 12 in the photovoltaic system 1 may be adjusted so that more
light is admitted for plants.

[0162] Alternatively, the electric power generated during the daytime by
the photovoltaic system 1 (photovoltaic modules 12) in the light
admitting apparatus 50 may be stored in a rechargeable battery where
possible so that the plants PL can be illuminated as needed at night.

INDUSTRIAL APPLICABILITY

[0163] The present invention (photovoltaic module, photovoltaic system,
light admitting apparatus) may be used for a photovoltaic module, a
photovoltaic system, and a light admitting apparatus, for example, for
outdoor installation to convert sunlight to electricity. The present
invention is effectively applicable for electric power generation from a
clean energy source.